Antioxidant activity of isoflavones and their major metabolites using different in vitro assays
Antioxidant activity of isoflavones and their major metabolites using different in vitro assays
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DOI：
10.1021/jf053112o
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发表时间：
2006-04-19
影响因子：
6.1
通讯作者：
Kulling, SE
中科院分区：
文献类型：
--
作者：
Rüfer, CE;Kulling, SE
异黄酮类植物雌激素主要存在于大豆和三叶草中，是被广泛研究的植物化学物质。大豆中发现的主要异黄酮染料木素和大豆苷元受到了最多的关注。然而，它们在肠道和肝脏中经历了广泛的代谢，这可能会影响它们的生物学特性，例如它们的抗氧化能力。此外，其他天然存在的异黄酮类化合物，如大豆中的黄豆黄素或红三叶草中的生物粘附素A，其生物活性尚未得到详细研究。本研究的目的是研究六种天然异黄酮及其相应的氧化和细菌代谢产物的抗氧化活性。采用氧自由基吸收能力测定以及以共轭双烯和硫代巴比妥酸反应产物为终点的低密度脂蛋白的体外氧化。染料木素和大豆苷元以及木酚的氧化代谢产物在所有三种测定中都显示出最高的抗氧化活性。除极少数例外，它们比阳性对照槲皮素和抗坏血酸更有效。芦荟素是大豆苷元的4‘-O-甲基醚，其抗氧化性能最差。由于作为有效抗氧化剂的异黄酮在食用大豆制品的受试者血浆中的浓度范围内具有明显的抗氧化效果，因此这种生物学活性可能具有生理意义。
Isoflavone phytoestrogens found mainly in soybeans and clover are widely studied phytochemicals. Genistein and daidzein, the major isoflavones found in soy, have received the most attention. However, they undergo extensive metabolism in the intestine and the liver, which might affect their biological properties, e.g. their antioxidant capacities. Furthermore, the biological activities of other naturally occurring isoflavones, for instance, glycitein from soy or biochanin A from red clover, have not yet been studied in detail. The aim of this study was to investigate the antioxidant activities of six naturally occurring isoflavones and their corresponding oxidative and bacterial metabolites. The oxygen radical absorbance capacity assay as well as the in vitro oxidation of low density lipoproteins with the conjugated diene and the thiobarbituric acid reacting substances formation as end points were used. The oxidative metabolites of genistein and daidzein as well as equol exhibited the highest antioxidant activities in all three assays. With few exceptions, they were more effective than the positive controls quercetin and ascorbic acid. Formononetin, the 4'-O-methyl ether of daidzein, showed the lowest antioxidant property. Because the antioxidant efficacy of isoflavones as effective antioxidants is evident at concentrations well within the range found in the plasma of subjects consuming soy products, this biological activity could be of physiological relevance.